This is a mixed purpose kit with large arms for 30MM/HG scale models and two other categories of parts - You generally want this for the arms, not the rest.
Since the arms and hands themselves are white, it only really goes with a couple of kits. I intended to try and use them for a Provedel, but they're only really compatible with stuff like the white Space Portanova or an HG equivalent.
1. Arms:
Right and left arm with two oversized hands each. The arms have a three part structure with a nice double bend and built in shoulder pivot to lift them about 90 degrees.
There's a pair of holding hands that hold regular straight handle weapons (will even fit some closed handles, as well as the included one) and a pair of fists.
Both pairs have a C-clip anchor point and two pairs of C-clip joints, one with ball joints and the other with 3mm pegs.
Why? Great question, but that means you can put one pair on 3mm hard points and stick them straight out of the sides of the head on some models, if you wanted to. Or give a 30MS girl a butt hand so she can pat herself.
An extra pair of ball joints would've perhaps been preferable, since removing C-clips and reattaching them, weakens and often breaks them.
There are additional shoulder armor pieces, which are somewhat awkwardly shaped.
2. Cannon:
This is a two-part cannon, main body and barrel, connected by an adapter piece with a 3mm hole to weapon tab. There is also a closed handle with a C-clip connection point and the main body has three anchor points, as well as multiple 3mm hard points and holes for tabs.
While the overall shape and style is sci-fi-ambiguous, like a lot of early 30MM stuff is, the overall length of the combined cannon is 16cm and far larger than most MG scaled weaponry, making this a significant piece of hardware.
As the product images show, the cannon friction fits over the wrist of either large arm (yet another non-standard Bandai connection) and the adapter piece on the body of the cannon then allows you to fit anything with a 3mm peg, such as aforementioned hand C-clips, or whatever you want.
3. Heads:
I don't know what these heads are, they might be unique to this kit (though they're definitely Earth Alliance themed), but they're not the standard Alto or Rabiot head. They might be from the Commander kits.
You get two head back-sides, two white front sides and a grey (why?) front side. You also get a transparent green visor and an opaque grey visor for the white faces.
Conclusion:
The white plastic makes sense, because there are white 30MM models, even if there aren't that many variations, and also because white plastic is easier to cover with paint.
It would've been nice with a different attachment option than built in ball joints, so you could've plugged the arms into 3mm hard points.
For all the connection points that the cannon has, there isn't a single 3mm adapter to just plug it onto a backpack as an over-the-shoulder or on-the-back artillery gun. Supply your own, I guess.
Aesthetically it looks like a lot of 30MM equipment does, like modular plastic toy pieces. The two cannons from the Heavy Weapon 1 kit do a much better job, visually, even if they aren't as large.
The specifics of how things connect limit this kit a bit too much, when it should've all been more universal, but all the things do have their uses.